Retractable soot blowers (which term includes so-called water lances) must sometimes be installed close to walls or other parts which could be eroded or otherwise damaged by the jet from the blower. In order to prevent such impingement it is desirable to establish a pattern of travel for the blower nozzle such that rotary motion of the lance is confined to a specifically limited angle and to a predetermined angular position. It is also desirable to similarly restrict the angular pattern of the lance under conditions such that portions of the full 360 degree possible pattern would not cause the jet to impinge any cleanable area.
In the past some constructions have been employed which although permitting full 360 degree rotation of the lance, interrupt the feed of blowing medium during a desired portion of the rotation. This is not feasible under the high temperatures imposed on the lance in many modern installations, because of damage which the lance would suffer if the cooling effect of blowing medium were interrupted while the lance is in the boiler.
Although various constructions have been devised heretofore for limiting the angular travel of rotary blowers, these have not been of a character which would permit simple adaptation thereof to standard types of long retracting blowers.
It is accordingly an object of the present invention to provide improved accessory transmission means for a standard type of blower which limits the angular blast pattern to a predetermined path, which means is so designed that no substantial modifications of the standardized blower construction are required. The efficiency of the boiler and safety of personnel are safeguarded by the fact that this invention permits use of standard soot blower components of proven design, while the cost of providing the limited angular pattern feature is minimized.
Other objects and advantages of this invention will become apparent to those skilled in the art upon consideration of the present disclosure in its entirety.